Commit | Line | Data |
---|---|---|
457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* Kernel thread helper functions. |
3 | * Copyright (C) 2004 IBM Corporation, Rusty Russell. | |
9bf5b9eb | 4 | * Copyright (C) 2009 Red Hat, Inc. |
1da177e4 | 5 | * |
73c27992 | 6 | * Creation is done via kthreadd, so that we get a clean environment |
1da177e4 LT |
7 | * even if we're invoked from userspace (think modprobe, hotplug cpu, |
8 | * etc.). | |
9 | */ | |
ae7e81c0 | 10 | #include <uapi/linux/sched/types.h> |
9bf5b9eb CH |
11 | #include <linux/mm.h> |
12 | #include <linux/mmu_context.h> | |
1da177e4 | 13 | #include <linux/sched.h> |
9bf5b9eb | 14 | #include <linux/sched/mm.h> |
29930025 | 15 | #include <linux/sched/task.h> |
1da177e4 LT |
16 | #include <linux/kthread.h> |
17 | #include <linux/completion.h> | |
18 | #include <linux/err.h> | |
8af0c18a | 19 | #include <linux/cgroup.h> |
58568d2a | 20 | #include <linux/cpuset.h> |
1da177e4 LT |
21 | #include <linux/unistd.h> |
22 | #include <linux/file.h> | |
9984de1a | 23 | #include <linux/export.h> |
97d1f15b | 24 | #include <linux/mutex.h> |
b56c0d89 TH |
25 | #include <linux/slab.h> |
26 | #include <linux/freezer.h> | |
a74fb73c | 27 | #include <linux/ptrace.h> |
cd42d559 | 28 | #include <linux/uaccess.h> |
98fa15f3 | 29 | #include <linux/numa.h> |
9cc5b865 | 30 | #include <linux/sched/isolation.h> |
ad8d75ff | 31 | #include <trace/events/sched.h> |
1da177e4 | 32 | |
9bf5b9eb | 33 | |
73c27992 EB |
34 | static DEFINE_SPINLOCK(kthread_create_lock); |
35 | static LIST_HEAD(kthread_create_list); | |
36 | struct task_struct *kthreadd_task; | |
1da177e4 LT |
37 | |
38 | struct kthread_create_info | |
39 | { | |
73c27992 | 40 | /* Information passed to kthread() from kthreadd. */ |
73e0c116 | 41 | char *full_name; |
1da177e4 LT |
42 | int (*threadfn)(void *data); |
43 | void *data; | |
207205a2 | 44 | int node; |
1da177e4 | 45 | |
73c27992 | 46 | /* Result passed back to kthread_create() from kthreadd. */ |
1da177e4 | 47 | struct task_struct *result; |
786235ee | 48 | struct completion *done; |
65f27f38 | 49 | |
73c27992 | 50 | struct list_head list; |
1da177e4 LT |
51 | }; |
52 | ||
63706172 | 53 | struct kthread { |
2a1d4460 TG |
54 | unsigned long flags; |
55 | unsigned int cpu; | |
6b124879 | 56 | int result; |
52782c92 | 57 | int (*threadfn)(void *); |
82805ab7 | 58 | void *data; |
2a1d4460 | 59 | struct completion parked; |
63706172 | 60 | struct completion exited; |
0b508bc9 | 61 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
62 | struct cgroup_subsys_state *blkcg_css; |
63 | #endif | |
d6986ce2 YS |
64 | /* To store the full name if task comm is truncated. */ |
65 | char *full_name; | |
1da177e4 LT |
66 | }; |
67 | ||
2a1d4460 TG |
68 | enum KTHREAD_BITS { |
69 | KTHREAD_IS_PER_CPU = 0, | |
70 | KTHREAD_SHOULD_STOP, | |
71 | KTHREAD_SHOULD_PARK, | |
2a1d4460 TG |
72 | }; |
73 | ||
4ecdafc8 ON |
74 | static inline struct kthread *to_kthread(struct task_struct *k) |
75 | { | |
1da5c46f | 76 | WARN_ON(!(k->flags & PF_KTHREAD)); |
e32cf5df | 77 | return k->worker_private; |
4ecdafc8 ON |
78 | } |
79 | ||
3a7956e2 PZ |
80 | /* |
81 | * Variant of to_kthread() that doesn't assume @p is a kthread. | |
82 | * | |
83 | * Per construction; when: | |
84 | * | |
e32cf5df | 85 | * (p->flags & PF_KTHREAD) && p->worker_private |
3a7956e2 PZ |
86 | * |
87 | * the task is both a kthread and struct kthread is persistent. However | |
88 | * PF_KTHREAD on it's own is not, kernel_thread() can exec() (See umh.c and | |
89 | * begin_new_exec()). | |
90 | */ | |
91 | static inline struct kthread *__to_kthread(struct task_struct *p) | |
92 | { | |
e32cf5df | 93 | void *kthread = p->worker_private; |
3a7956e2 PZ |
94 | if (kthread && !(p->flags & PF_KTHREAD)) |
95 | kthread = NULL; | |
96 | return kthread; | |
97 | } | |
98 | ||
d6986ce2 YS |
99 | void get_kthread_comm(char *buf, size_t buf_size, struct task_struct *tsk) |
100 | { | |
101 | struct kthread *kthread = to_kthread(tsk); | |
102 | ||
103 | if (!kthread || !kthread->full_name) { | |
104 | __get_task_comm(buf, buf_size, tsk); | |
105 | return; | |
106 | } | |
107 | ||
108 | strscpy_pad(buf, kthread->full_name, buf_size); | |
109 | } | |
110 | ||
40966e31 | 111 | bool set_kthread_struct(struct task_struct *p) |
00b89fe0 VS |
112 | { |
113 | struct kthread *kthread; | |
114 | ||
40966e31 EB |
115 | if (WARN_ON_ONCE(to_kthread(p))) |
116 | return false; | |
00b89fe0 VS |
117 | |
118 | kthread = kzalloc(sizeof(*kthread), GFP_KERNEL); | |
40966e31 EB |
119 | if (!kthread) |
120 | return false; | |
121 | ||
122 | init_completion(&kthread->exited); | |
123 | init_completion(&kthread->parked); | |
124 | p->vfork_done = &kthread->exited; | |
125 | ||
e32cf5df | 126 | p->worker_private = kthread; |
40966e31 | 127 | return true; |
00b89fe0 VS |
128 | } |
129 | ||
1da5c46f ON |
130 | void free_kthread_struct(struct task_struct *k) |
131 | { | |
05e3db95 SL |
132 | struct kthread *kthread; |
133 | ||
1da5c46f | 134 | /* |
40966e31 | 135 | * Can be NULL if kmalloc() in set_kthread_struct() failed. |
1da5c46f | 136 | */ |
05e3db95 | 137 | kthread = to_kthread(k); |
d6986ce2 YS |
138 | if (!kthread) |
139 | return; | |
140 | ||
0b508bc9 | 141 | #ifdef CONFIG_BLK_CGROUP |
d6986ce2 | 142 | WARN_ON_ONCE(kthread->blkcg_css); |
05e3db95 | 143 | #endif |
e32cf5df | 144 | k->worker_private = NULL; |
d6986ce2 | 145 | kfree(kthread->full_name); |
05e3db95 | 146 | kfree(kthread); |
1da5c46f ON |
147 | } |
148 | ||
9e37bd30 RD |
149 | /** |
150 | * kthread_should_stop - should this kthread return now? | |
151 | * | |
72fd4a35 | 152 | * When someone calls kthread_stop() on your kthread, it will be woken |
9e37bd30 RD |
153 | * and this will return true. You should then return, and your return |
154 | * value will be passed through to kthread_stop(). | |
155 | */ | |
2a1d4460 | 156 | bool kthread_should_stop(void) |
1da177e4 | 157 | { |
2a1d4460 | 158 | return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags); |
1da177e4 LT |
159 | } |
160 | EXPORT_SYMBOL(kthread_should_stop); | |
161 | ||
0121805d MK |
162 | bool __kthread_should_park(struct task_struct *k) |
163 | { | |
164 | return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(k)->flags); | |
165 | } | |
166 | EXPORT_SYMBOL_GPL(__kthread_should_park); | |
167 | ||
2a1d4460 TG |
168 | /** |
169 | * kthread_should_park - should this kthread park now? | |
170 | * | |
171 | * When someone calls kthread_park() on your kthread, it will be woken | |
172 | * and this will return true. You should then do the necessary | |
173 | * cleanup and call kthread_parkme() | |
174 | * | |
175 | * Similar to kthread_should_stop(), but this keeps the thread alive | |
176 | * and in a park position. kthread_unpark() "restarts" the thread and | |
177 | * calls the thread function again. | |
178 | */ | |
179 | bool kthread_should_park(void) | |
180 | { | |
0121805d | 181 | return __kthread_should_park(current); |
2a1d4460 | 182 | } |
18896451 | 183 | EXPORT_SYMBOL_GPL(kthread_should_park); |
2a1d4460 | 184 | |
8a32c441 TH |
185 | /** |
186 | * kthread_freezable_should_stop - should this freezable kthread return now? | |
187 | * @was_frozen: optional out parameter, indicates whether %current was frozen | |
188 | * | |
189 | * kthread_should_stop() for freezable kthreads, which will enter | |
190 | * refrigerator if necessary. This function is safe from kthread_stop() / | |
191 | * freezer deadlock and freezable kthreads should use this function instead | |
192 | * of calling try_to_freeze() directly. | |
193 | */ | |
194 | bool kthread_freezable_should_stop(bool *was_frozen) | |
195 | { | |
196 | bool frozen = false; | |
197 | ||
198 | might_sleep(); | |
199 | ||
200 | if (unlikely(freezing(current))) | |
201 | frozen = __refrigerator(true); | |
202 | ||
203 | if (was_frozen) | |
204 | *was_frozen = frozen; | |
205 | ||
206 | return kthread_should_stop(); | |
207 | } | |
208 | EXPORT_SYMBOL_GPL(kthread_freezable_should_stop); | |
209 | ||
52782c92 BF |
210 | /** |
211 | * kthread_func - return the function specified on kthread creation | |
212 | * @task: kthread task in question | |
213 | * | |
214 | * Returns NULL if the task is not a kthread. | |
215 | */ | |
216 | void *kthread_func(struct task_struct *task) | |
217 | { | |
3a7956e2 PZ |
218 | struct kthread *kthread = __to_kthread(task); |
219 | if (kthread) | |
220 | return kthread->threadfn; | |
52782c92 BF |
221 | return NULL; |
222 | } | |
223 | EXPORT_SYMBOL_GPL(kthread_func); | |
224 | ||
82805ab7 TH |
225 | /** |
226 | * kthread_data - return data value specified on kthread creation | |
227 | * @task: kthread task in question | |
228 | * | |
229 | * Return the data value specified when kthread @task was created. | |
230 | * The caller is responsible for ensuring the validity of @task when | |
231 | * calling this function. | |
232 | */ | |
233 | void *kthread_data(struct task_struct *task) | |
234 | { | |
235 | return to_kthread(task)->data; | |
236 | } | |
52782c92 | 237 | EXPORT_SYMBOL_GPL(kthread_data); |
82805ab7 | 238 | |
cd42d559 | 239 | /** |
e700591a | 240 | * kthread_probe_data - speculative version of kthread_data() |
cd42d559 TH |
241 | * @task: possible kthread task in question |
242 | * | |
243 | * @task could be a kthread task. Return the data value specified when it | |
244 | * was created if accessible. If @task isn't a kthread task or its data is | |
245 | * inaccessible for any reason, %NULL is returned. This function requires | |
246 | * that @task itself is safe to dereference. | |
247 | */ | |
e700591a | 248 | void *kthread_probe_data(struct task_struct *task) |
cd42d559 | 249 | { |
3a7956e2 | 250 | struct kthread *kthread = __to_kthread(task); |
cd42d559 TH |
251 | void *data = NULL; |
252 | ||
3a7956e2 PZ |
253 | if (kthread) |
254 | copy_from_kernel_nofault(&data, &kthread->data, sizeof(data)); | |
cd42d559 TH |
255 | return data; |
256 | } | |
257 | ||
2a1d4460 TG |
258 | static void __kthread_parkme(struct kthread *self) |
259 | { | |
741a76b3 | 260 | for (;;) { |
1cef1150 PZ |
261 | /* |
262 | * TASK_PARKED is a special state; we must serialize against | |
263 | * possible pending wakeups to avoid store-store collisions on | |
264 | * task->state. | |
265 | * | |
266 | * Such a collision might possibly result in the task state | |
267 | * changin from TASK_PARKED and us failing the | |
268 | * wait_task_inactive() in kthread_park(). | |
269 | */ | |
270 | set_special_state(TASK_PARKED); | |
741a76b3 PZ |
271 | if (!test_bit(KTHREAD_SHOULD_PARK, &self->flags)) |
272 | break; | |
1cef1150 | 273 | |
26c7295b LC |
274 | /* |
275 | * Thread is going to call schedule(), do not preempt it, | |
276 | * or the caller of kthread_park() may spend more time in | |
277 | * wait_task_inactive(). | |
278 | */ | |
279 | preempt_disable(); | |
f83ee19b | 280 | complete(&self->parked); |
26c7295b LC |
281 | schedule_preempt_disabled(); |
282 | preempt_enable(); | |
2a1d4460 | 283 | } |
2a1d4460 TG |
284 | __set_current_state(TASK_RUNNING); |
285 | } | |
286 | ||
287 | void kthread_parkme(void) | |
288 | { | |
289 | __kthread_parkme(to_kthread(current)); | |
290 | } | |
18896451 | 291 | EXPORT_SYMBOL_GPL(kthread_parkme); |
2a1d4460 | 292 | |
bbda86e9 EB |
293 | /** |
294 | * kthread_exit - Cause the current kthread return @result to kthread_stop(). | |
295 | * @result: The integer value to return to kthread_stop(). | |
296 | * | |
297 | * While kthread_exit can be called directly, it exists so that | |
298 | * functions which do some additional work in non-modular code such as | |
299 | * module_put_and_kthread_exit can be implemented. | |
300 | * | |
301 | * Does not return. | |
302 | */ | |
303 | void __noreturn kthread_exit(long result) | |
304 | { | |
6b124879 EB |
305 | struct kthread *kthread = to_kthread(current); |
306 | kthread->result = result; | |
307 | do_exit(0); | |
bbda86e9 EB |
308 | } |
309 | ||
cead1855 | 310 | /** |
5eb6f228 | 311 | * kthread_complete_and_exit - Exit the current kthread. |
cead1855 EB |
312 | * @comp: Completion to complete |
313 | * @code: The integer value to return to kthread_stop(). | |
314 | * | |
315 | * If present complete @comp and the reuturn code to kthread_stop(). | |
316 | * | |
317 | * A kernel thread whose module may be removed after the completion of | |
318 | * @comp can use this function exit safely. | |
319 | * | |
320 | * Does not return. | |
321 | */ | |
322 | void __noreturn kthread_complete_and_exit(struct completion *comp, long code) | |
323 | { | |
324 | if (comp) | |
325 | complete(comp); | |
326 | ||
327 | kthread_exit(code); | |
328 | } | |
329 | EXPORT_SYMBOL(kthread_complete_and_exit); | |
330 | ||
1da177e4 LT |
331 | static int kthread(void *_create) |
332 | { | |
1a7243ca | 333 | static const struct sched_param param = { .sched_priority = 0 }; |
63706172 | 334 | /* Copy data: it's on kthread's stack */ |
1da177e4 | 335 | struct kthread_create_info *create = _create; |
63706172 ON |
336 | int (*threadfn)(void *data) = create->threadfn; |
337 | void *data = create->data; | |
786235ee | 338 | struct completion *done; |
1da5c46f | 339 | struct kthread *self; |
63706172 | 340 | int ret; |
1da177e4 | 341 | |
00b89fe0 | 342 | self = to_kthread(current); |
1da177e4 | 343 | |
d25c83c6 | 344 | /* Release the structure when caller killed by a fatal signal. */ |
786235ee TH |
345 | done = xchg(&create->done, NULL); |
346 | if (!done) { | |
73e0c116 | 347 | kfree(create->full_name); |
786235ee | 348 | kfree(create); |
bbda86e9 | 349 | kthread_exit(-EINTR); |
1da5c46f ON |
350 | } |
351 | ||
73e0c116 | 352 | self->full_name = create->full_name; |
52782c92 | 353 | self->threadfn = threadfn; |
1da5c46f | 354 | self->data = data; |
1da5c46f | 355 | |
1a7243ca SAS |
356 | /* |
357 | * The new thread inherited kthreadd's priority and CPU mask. Reset | |
358 | * back to default in case they have been changed. | |
359 | */ | |
360 | sched_setscheduler_nocheck(current, SCHED_NORMAL, ¶m); | |
04d4e665 | 361 | set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_TYPE_KTHREAD)); |
1a7243ca | 362 | |
1da177e4 | 363 | /* OK, tell user we're spawned, wait for stop or wakeup */ |
a076e4bc | 364 | __set_current_state(TASK_UNINTERRUPTIBLE); |
3217ab97 | 365 | create->result = current; |
26c7295b LC |
366 | /* |
367 | * Thread is going to call schedule(), do not preempt it, | |
368 | * or the creator may spend more time in wait_task_inactive(). | |
369 | */ | |
370 | preempt_disable(); | |
786235ee | 371 | complete(done); |
26c7295b LC |
372 | schedule_preempt_disabled(); |
373 | preempt_enable(); | |
1da177e4 | 374 | |
63706172 | 375 | ret = -EINTR; |
1da5c46f | 376 | if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) { |
77f88796 | 377 | cgroup_kthread_ready(); |
1da5c46f | 378 | __kthread_parkme(self); |
2a1d4460 TG |
379 | ret = threadfn(data); |
380 | } | |
bbda86e9 | 381 | kthread_exit(ret); |
1da177e4 LT |
382 | } |
383 | ||
cb5021ca | 384 | /* called from kernel_clone() to get node information for about to be created task */ |
207205a2 ED |
385 | int tsk_fork_get_node(struct task_struct *tsk) |
386 | { | |
387 | #ifdef CONFIG_NUMA | |
388 | if (tsk == kthreadd_task) | |
389 | return tsk->pref_node_fork; | |
390 | #endif | |
81c98869 | 391 | return NUMA_NO_NODE; |
207205a2 ED |
392 | } |
393 | ||
73c27992 | 394 | static void create_kthread(struct kthread_create_info *create) |
1da177e4 | 395 | { |
1da177e4 LT |
396 | int pid; |
397 | ||
207205a2 ED |
398 | #ifdef CONFIG_NUMA |
399 | current->pref_node_fork = create->node; | |
400 | #endif | |
1da177e4 | 401 | /* We want our own signal handler (we take no signals by default). */ |
73e0c116 | 402 | pid = kernel_thread(kthread, create, create->full_name, |
cf587db2 | 403 | CLONE_FS | CLONE_FILES | SIGCHLD); |
cdd140bd | 404 | if (pid < 0) { |
d25c83c6 | 405 | /* Release the structure when caller killed by a fatal signal. */ |
786235ee TH |
406 | struct completion *done = xchg(&create->done, NULL); |
407 | ||
73e0c116 | 408 | kfree(create->full_name); |
786235ee TH |
409 | if (!done) { |
410 | kfree(create); | |
411 | return; | |
412 | } | |
1da177e4 | 413 | create->result = ERR_PTR(pid); |
786235ee | 414 | complete(done); |
cdd140bd | 415 | } |
1da177e4 LT |
416 | } |
417 | ||
c0b942a7 NI |
418 | static __printf(4, 0) |
419 | struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data), | |
255451e4 PM |
420 | void *data, int node, |
421 | const char namefmt[], | |
422 | va_list args) | |
1da177e4 | 423 | { |
786235ee TH |
424 | DECLARE_COMPLETION_ONSTACK(done); |
425 | struct task_struct *task; | |
426 | struct kthread_create_info *create = kmalloc(sizeof(*create), | |
427 | GFP_KERNEL); | |
428 | ||
429 | if (!create) | |
430 | return ERR_PTR(-ENOMEM); | |
431 | create->threadfn = threadfn; | |
432 | create->data = data; | |
433 | create->node = node; | |
434 | create->done = &done; | |
73e0c116 MC |
435 | create->full_name = kvasprintf(GFP_KERNEL, namefmt, args); |
436 | if (!create->full_name) { | |
437 | task = ERR_PTR(-ENOMEM); | |
438 | goto free_create; | |
439 | } | |
73c27992 EB |
440 | |
441 | spin_lock(&kthread_create_lock); | |
786235ee | 442 | list_add_tail(&create->list, &kthread_create_list); |
73c27992 EB |
443 | spin_unlock(&kthread_create_lock); |
444 | ||
cbd9b67b | 445 | wake_up_process(kthreadd_task); |
786235ee TH |
446 | /* |
447 | * Wait for completion in killable state, for I might be chosen by | |
448 | * the OOM killer while kthreadd is trying to allocate memory for | |
449 | * new kernel thread. | |
450 | */ | |
451 | if (unlikely(wait_for_completion_killable(&done))) { | |
452 | /* | |
d25c83c6 PM |
453 | * If I was killed by a fatal signal before kthreadd (or new |
454 | * kernel thread) calls complete(), leave the cleanup of this | |
455 | * structure to that thread. | |
786235ee TH |
456 | */ |
457 | if (xchg(&create->done, NULL)) | |
8fe6929c | 458 | return ERR_PTR(-EINTR); |
786235ee TH |
459 | /* |
460 | * kthreadd (or new kernel thread) will call complete() | |
461 | * shortly. | |
462 | */ | |
463 | wait_for_completion(&done); | |
464 | } | |
465 | task = create->result; | |
73e0c116 | 466 | free_create: |
786235ee TH |
467 | kfree(create); |
468 | return task; | |
1da177e4 | 469 | } |
255451e4 PM |
470 | |
471 | /** | |
472 | * kthread_create_on_node - create a kthread. | |
473 | * @threadfn: the function to run until signal_pending(current). | |
474 | * @data: data ptr for @threadfn. | |
475 | * @node: task and thread structures for the thread are allocated on this node | |
476 | * @namefmt: printf-style name for the thread. | |
477 | * | |
478 | * Description: This helper function creates and names a kernel | |
479 | * thread. The thread will be stopped: use wake_up_process() to start | |
480 | * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and | |
481 | * is affine to all CPUs. | |
482 | * | |
483 | * If thread is going to be bound on a particular cpu, give its node | |
484 | * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE. | |
485 | * When woken, the thread will run @threadfn() with @data as its | |
111e7049 | 486 | * argument. @threadfn() can either return directly if it is a |
255451e4 PM |
487 | * standalone thread for which no one will call kthread_stop(), or |
488 | * return when 'kthread_should_stop()' is true (which means | |
489 | * kthread_stop() has been called). The return value should be zero | |
490 | * or a negative error number; it will be passed to kthread_stop(). | |
491 | * | |
492 | * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR). | |
493 | */ | |
494 | struct task_struct *kthread_create_on_node(int (*threadfn)(void *data), | |
495 | void *data, int node, | |
496 | const char namefmt[], | |
497 | ...) | |
498 | { | |
499 | struct task_struct *task; | |
500 | va_list args; | |
501 | ||
502 | va_start(args, namefmt); | |
503 | task = __kthread_create_on_node(threadfn, data, node, namefmt, args); | |
504 | va_end(args); | |
505 | ||
506 | return task; | |
507 | } | |
207205a2 | 508 | EXPORT_SYMBOL(kthread_create_on_node); |
1da177e4 | 509 | |
2f064a59 | 510 | static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, unsigned int state) |
2a1d4460 | 511 | { |
25834c73 PZ |
512 | unsigned long flags; |
513 | ||
f2530dc7 TG |
514 | if (!wait_task_inactive(p, state)) { |
515 | WARN_ON(1); | |
516 | return; | |
517 | } | |
25834c73 | 518 | |
2a1d4460 | 519 | /* It's safe because the task is inactive. */ |
25834c73 PZ |
520 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
521 | do_set_cpus_allowed(p, mask); | |
14a40ffc | 522 | p->flags |= PF_NO_SETAFFINITY; |
25834c73 PZ |
523 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
524 | } | |
525 | ||
2f064a59 | 526 | static void __kthread_bind(struct task_struct *p, unsigned int cpu, unsigned int state) |
25834c73 PZ |
527 | { |
528 | __kthread_bind_mask(p, cpumask_of(cpu), state); | |
529 | } | |
530 | ||
531 | void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask) | |
532 | { | |
533 | __kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE); | |
2a1d4460 TG |
534 | } |
535 | ||
881232b7 PZ |
536 | /** |
537 | * kthread_bind - bind a just-created kthread to a cpu. | |
538 | * @p: thread created by kthread_create(). | |
539 | * @cpu: cpu (might not be online, must be possible) for @k to run on. | |
540 | * | |
541 | * Description: This function is equivalent to set_cpus_allowed(), | |
542 | * except that @cpu doesn't need to be online, and the thread must be | |
543 | * stopped (i.e., just returned from kthread_create()). | |
544 | */ | |
545 | void kthread_bind(struct task_struct *p, unsigned int cpu) | |
546 | { | |
f2530dc7 | 547 | __kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE); |
881232b7 PZ |
548 | } |
549 | EXPORT_SYMBOL(kthread_bind); | |
550 | ||
2a1d4460 TG |
551 | /** |
552 | * kthread_create_on_cpu - Create a cpu bound kthread | |
553 | * @threadfn: the function to run until signal_pending(current). | |
554 | * @data: data ptr for @threadfn. | |
555 | * @cpu: The cpu on which the thread should be bound, | |
556 | * @namefmt: printf-style name for the thread. Format is restricted | |
557 | * to "name.*%u". Code fills in cpu number. | |
558 | * | |
559 | * Description: This helper function creates and names a kernel thread | |
2a1d4460 TG |
560 | */ |
561 | struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), | |
562 | void *data, unsigned int cpu, | |
563 | const char *namefmt) | |
564 | { | |
565 | struct task_struct *p; | |
566 | ||
10922838 | 567 | p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt, |
2a1d4460 TG |
568 | cpu); |
569 | if (IS_ERR(p)) | |
570 | return p; | |
a65d4096 PM |
571 | kthread_bind(p, cpu); |
572 | /* CPU hotplug need to bind once again when unparking the thread. */ | |
2a1d4460 | 573 | to_kthread(p)->cpu = cpu; |
2a1d4460 TG |
574 | return p; |
575 | } | |
800977f6 | 576 | EXPORT_SYMBOL(kthread_create_on_cpu); |
2a1d4460 | 577 | |
ac687e6e PZ |
578 | void kthread_set_per_cpu(struct task_struct *k, int cpu) |
579 | { | |
580 | struct kthread *kthread = to_kthread(k); | |
581 | if (!kthread) | |
582 | return; | |
583 | ||
584 | WARN_ON_ONCE(!(k->flags & PF_NO_SETAFFINITY)); | |
585 | ||
586 | if (cpu < 0) { | |
587 | clear_bit(KTHREAD_IS_PER_CPU, &kthread->flags); | |
588 | return; | |
589 | } | |
590 | ||
591 | kthread->cpu = cpu; | |
592 | set_bit(KTHREAD_IS_PER_CPU, &kthread->flags); | |
593 | } | |
594 | ||
3a7956e2 | 595 | bool kthread_is_per_cpu(struct task_struct *p) |
ac687e6e | 596 | { |
3a7956e2 | 597 | struct kthread *kthread = __to_kthread(p); |
ac687e6e PZ |
598 | if (!kthread) |
599 | return false; | |
600 | ||
601 | return test_bit(KTHREAD_IS_PER_CPU, &kthread->flags); | |
602 | } | |
603 | ||
cf380a4a ON |
604 | /** |
605 | * kthread_unpark - unpark a thread created by kthread_create(). | |
606 | * @k: thread created by kthread_create(). | |
607 | * | |
608 | * Sets kthread_should_park() for @k to return false, wakes it, and | |
609 | * waits for it to return. If the thread is marked percpu then its | |
610 | * bound to the cpu again. | |
611 | */ | |
612 | void kthread_unpark(struct task_struct *k) | |
f2530dc7 | 613 | { |
cf380a4a ON |
614 | struct kthread *kthread = to_kthread(k); |
615 | ||
f2530dc7 | 616 | /* |
85f1abe0 PZ |
617 | * Newly created kthread was parked when the CPU was offline. |
618 | * The binding was lost and we need to set it again. | |
f2530dc7 | 619 | */ |
85f1abe0 PZ |
620 | if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags)) |
621 | __kthread_bind(k, kthread->cpu, TASK_PARKED); | |
622 | ||
623 | clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags); | |
1cef1150 PZ |
624 | /* |
625 | * __kthread_parkme() will either see !SHOULD_PARK or get the wakeup. | |
626 | */ | |
85f1abe0 | 627 | wake_up_state(k, TASK_PARKED); |
f2530dc7 | 628 | } |
18896451 | 629 | EXPORT_SYMBOL_GPL(kthread_unpark); |
2a1d4460 TG |
630 | |
631 | /** | |
632 | * kthread_park - park a thread created by kthread_create(). | |
633 | * @k: thread created by kthread_create(). | |
634 | * | |
635 | * Sets kthread_should_park() for @k to return true, wakes it, and | |
636 | * waits for it to return. This can also be called after kthread_create() | |
637 | * instead of calling wake_up_process(): the thread will park without | |
638 | * calling threadfn(). | |
639 | * | |
640 | * Returns 0 if the thread is parked, -ENOSYS if the thread exited. | |
641 | * If called by the kthread itself just the park bit is set. | |
642 | */ | |
643 | int kthread_park(struct task_struct *k) | |
644 | { | |
cf380a4a ON |
645 | struct kthread *kthread = to_kthread(k); |
646 | ||
647 | if (WARN_ON(k->flags & PF_EXITING)) | |
648 | return -ENOSYS; | |
649 | ||
f83ee19b PZ |
650 | if (WARN_ON_ONCE(test_bit(KTHREAD_SHOULD_PARK, &kthread->flags))) |
651 | return -EBUSY; | |
652 | ||
85f1abe0 PZ |
653 | set_bit(KTHREAD_SHOULD_PARK, &kthread->flags); |
654 | if (k != current) { | |
655 | wake_up_process(k); | |
1cef1150 PZ |
656 | /* |
657 | * Wait for __kthread_parkme() to complete(), this means we | |
658 | * _will_ have TASK_PARKED and are about to call schedule(). | |
659 | */ | |
85f1abe0 | 660 | wait_for_completion(&kthread->parked); |
1cef1150 PZ |
661 | /* |
662 | * Now wait for that schedule() to complete and the task to | |
663 | * get scheduled out. | |
664 | */ | |
665 | WARN_ON_ONCE(!wait_task_inactive(k, TASK_PARKED)); | |
2a1d4460 | 666 | } |
cf380a4a ON |
667 | |
668 | return 0; | |
2a1d4460 | 669 | } |
18896451 | 670 | EXPORT_SYMBOL_GPL(kthread_park); |
2a1d4460 | 671 | |
9e37bd30 RD |
672 | /** |
673 | * kthread_stop - stop a thread created by kthread_create(). | |
674 | * @k: thread created by kthread_create(). | |
675 | * | |
676 | * Sets kthread_should_stop() for @k to return true, wakes it, and | |
9ae26027 ON |
677 | * waits for it to exit. This can also be called after kthread_create() |
678 | * instead of calling wake_up_process(): the thread will exit without | |
679 | * calling threadfn(). | |
680 | * | |
bbda86e9 | 681 | * If threadfn() may call kthread_exit() itself, the caller must ensure |
9ae26027 | 682 | * task_struct can't go away. |
9e37bd30 RD |
683 | * |
684 | * Returns the result of threadfn(), or %-EINTR if wake_up_process() | |
685 | * was never called. | |
686 | */ | |
1da177e4 LT |
687 | int kthread_stop(struct task_struct *k) |
688 | { | |
b5c5442b | 689 | struct kthread *kthread; |
1da177e4 LT |
690 | int ret; |
691 | ||
0a16b607 | 692 | trace_sched_kthread_stop(k); |
b5c5442b ON |
693 | |
694 | get_task_struct(k); | |
efb29fbf ON |
695 | kthread = to_kthread(k); |
696 | set_bit(KTHREAD_SHOULD_STOP, &kthread->flags); | |
cf380a4a | 697 | kthread_unpark(k); |
a7c01fa9 | 698 | set_tsk_thread_flag(k, TIF_NOTIFY_SIGNAL); |
efb29fbf ON |
699 | wake_up_process(k); |
700 | wait_for_completion(&kthread->exited); | |
6b124879 | 701 | ret = kthread->result; |
1da177e4 | 702 | put_task_struct(k); |
0a16b607 | 703 | |
b5c5442b | 704 | trace_sched_kthread_stop_ret(ret); |
1da177e4 LT |
705 | return ret; |
706 | } | |
52e92e57 | 707 | EXPORT_SYMBOL(kthread_stop); |
1da177e4 | 708 | |
e804a4a4 | 709 | int kthreadd(void *unused) |
1da177e4 | 710 | { |
73c27992 | 711 | struct task_struct *tsk = current; |
1da177e4 | 712 | |
e804a4a4 | 713 | /* Setup a clean context for our children to inherit. */ |
73c27992 | 714 | set_task_comm(tsk, "kthreadd"); |
10ab825b | 715 | ignore_signals(tsk); |
04d4e665 | 716 | set_cpus_allowed_ptr(tsk, housekeeping_cpumask(HK_TYPE_KTHREAD)); |
aee4faa4 | 717 | set_mems_allowed(node_states[N_MEMORY]); |
73c27992 | 718 | |
34b087e4 | 719 | current->flags |= PF_NOFREEZE; |
77f88796 | 720 | cgroup_init_kthreadd(); |
73c27992 EB |
721 | |
722 | for (;;) { | |
723 | set_current_state(TASK_INTERRUPTIBLE); | |
724 | if (list_empty(&kthread_create_list)) | |
725 | schedule(); | |
726 | __set_current_state(TASK_RUNNING); | |
727 | ||
728 | spin_lock(&kthread_create_lock); | |
729 | while (!list_empty(&kthread_create_list)) { | |
730 | struct kthread_create_info *create; | |
731 | ||
732 | create = list_entry(kthread_create_list.next, | |
733 | struct kthread_create_info, list); | |
734 | list_del_init(&create->list); | |
735 | spin_unlock(&kthread_create_lock); | |
736 | ||
737 | create_kthread(create); | |
738 | ||
739 | spin_lock(&kthread_create_lock); | |
740 | } | |
741 | spin_unlock(&kthread_create_lock); | |
742 | } | |
743 | ||
744 | return 0; | |
745 | } | |
b56c0d89 | 746 | |
3989144f | 747 | void __kthread_init_worker(struct kthread_worker *worker, |
4f32e9b1 YZ |
748 | const char *name, |
749 | struct lock_class_key *key) | |
750 | { | |
dbf52682 | 751 | memset(worker, 0, sizeof(struct kthread_worker)); |
fe99a4f4 | 752 | raw_spin_lock_init(&worker->lock); |
4f32e9b1 YZ |
753 | lockdep_set_class_and_name(&worker->lock, key, name); |
754 | INIT_LIST_HEAD(&worker->work_list); | |
22597dc3 | 755 | INIT_LIST_HEAD(&worker->delayed_work_list); |
4f32e9b1 | 756 | } |
3989144f | 757 | EXPORT_SYMBOL_GPL(__kthread_init_worker); |
4f32e9b1 | 758 | |
b56c0d89 TH |
759 | /** |
760 | * kthread_worker_fn - kthread function to process kthread_worker | |
761 | * @worker_ptr: pointer to initialized kthread_worker | |
762 | * | |
fbae2d44 PM |
763 | * This function implements the main cycle of kthread worker. It processes |
764 | * work_list until it is stopped with kthread_stop(). It sleeps when the queue | |
765 | * is empty. | |
b56c0d89 | 766 | * |
fbae2d44 PM |
767 | * The works are not allowed to keep any locks, disable preemption or interrupts |
768 | * when they finish. There is defined a safe point for freezing when one work | |
769 | * finishes and before a new one is started. | |
8197b3d4 PM |
770 | * |
771 | * Also the works must not be handled by more than one worker at the same time, | |
772 | * see also kthread_queue_work(). | |
b56c0d89 TH |
773 | */ |
774 | int kthread_worker_fn(void *worker_ptr) | |
775 | { | |
776 | struct kthread_worker *worker = worker_ptr; | |
777 | struct kthread_work *work; | |
778 | ||
fbae2d44 PM |
779 | /* |
780 | * FIXME: Update the check and remove the assignment when all kthread | |
781 | * worker users are created using kthread_create_worker*() functions. | |
782 | */ | |
783 | WARN_ON(worker->task && worker->task != current); | |
b56c0d89 | 784 | worker->task = current; |
dbf52682 PM |
785 | |
786 | if (worker->flags & KTW_FREEZABLE) | |
787 | set_freezable(); | |
788 | ||
b56c0d89 TH |
789 | repeat: |
790 | set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */ | |
791 | ||
792 | if (kthread_should_stop()) { | |
793 | __set_current_state(TASK_RUNNING); | |
fe99a4f4 | 794 | raw_spin_lock_irq(&worker->lock); |
b56c0d89 | 795 | worker->task = NULL; |
fe99a4f4 | 796 | raw_spin_unlock_irq(&worker->lock); |
b56c0d89 TH |
797 | return 0; |
798 | } | |
799 | ||
800 | work = NULL; | |
fe99a4f4 | 801 | raw_spin_lock_irq(&worker->lock); |
b56c0d89 TH |
802 | if (!list_empty(&worker->work_list)) { |
803 | work = list_first_entry(&worker->work_list, | |
804 | struct kthread_work, node); | |
805 | list_del_init(&work->node); | |
806 | } | |
46f3d976 | 807 | worker->current_work = work; |
fe99a4f4 | 808 | raw_spin_unlock_irq(&worker->lock); |
b56c0d89 TH |
809 | |
810 | if (work) { | |
f630c7c6 | 811 | kthread_work_func_t func = work->func; |
b56c0d89 | 812 | __set_current_state(TASK_RUNNING); |
f630c7c6 | 813 | trace_sched_kthread_work_execute_start(work); |
b56c0d89 | 814 | work->func(work); |
f630c7c6 RC |
815 | /* |
816 | * Avoid dereferencing work after this point. The trace | |
817 | * event only cares about the address. | |
818 | */ | |
819 | trace_sched_kthread_work_execute_end(work, func); | |
b56c0d89 TH |
820 | } else if (!freezing(current)) |
821 | schedule(); | |
822 | ||
823 | try_to_freeze(); | |
22cf8bc6 | 824 | cond_resched(); |
b56c0d89 TH |
825 | goto repeat; |
826 | } | |
827 | EXPORT_SYMBOL_GPL(kthread_worker_fn); | |
828 | ||
c0b942a7 | 829 | static __printf(3, 0) struct kthread_worker * |
dbf52682 PM |
830 | __kthread_create_worker(int cpu, unsigned int flags, |
831 | const char namefmt[], va_list args) | |
fbae2d44 PM |
832 | { |
833 | struct kthread_worker *worker; | |
834 | struct task_struct *task; | |
98fa15f3 | 835 | int node = NUMA_NO_NODE; |
fbae2d44 PM |
836 | |
837 | worker = kzalloc(sizeof(*worker), GFP_KERNEL); | |
838 | if (!worker) | |
839 | return ERR_PTR(-ENOMEM); | |
840 | ||
841 | kthread_init_worker(worker); | |
842 | ||
8fb9dcbd ON |
843 | if (cpu >= 0) |
844 | node = cpu_to_node(cpu); | |
fbae2d44 | 845 | |
8fb9dcbd ON |
846 | task = __kthread_create_on_node(kthread_worker_fn, worker, |
847 | node, namefmt, args); | |
fbae2d44 PM |
848 | if (IS_ERR(task)) |
849 | goto fail_task; | |
850 | ||
8fb9dcbd ON |
851 | if (cpu >= 0) |
852 | kthread_bind(task, cpu); | |
853 | ||
dbf52682 | 854 | worker->flags = flags; |
fbae2d44 PM |
855 | worker->task = task; |
856 | wake_up_process(task); | |
857 | return worker; | |
858 | ||
859 | fail_task: | |
860 | kfree(worker); | |
861 | return ERR_CAST(task); | |
862 | } | |
863 | ||
864 | /** | |
865 | * kthread_create_worker - create a kthread worker | |
dbf52682 | 866 | * @flags: flags modifying the default behavior of the worker |
fbae2d44 PM |
867 | * @namefmt: printf-style name for the kthread worker (task). |
868 | * | |
869 | * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) | |
870 | * when the needed structures could not get allocated, and ERR_PTR(-EINTR) | |
d25c83c6 | 871 | * when the caller was killed by a fatal signal. |
fbae2d44 PM |
872 | */ |
873 | struct kthread_worker * | |
dbf52682 | 874 | kthread_create_worker(unsigned int flags, const char namefmt[], ...) |
fbae2d44 PM |
875 | { |
876 | struct kthread_worker *worker; | |
877 | va_list args; | |
878 | ||
879 | va_start(args, namefmt); | |
dbf52682 | 880 | worker = __kthread_create_worker(-1, flags, namefmt, args); |
fbae2d44 PM |
881 | va_end(args); |
882 | ||
883 | return worker; | |
884 | } | |
885 | EXPORT_SYMBOL(kthread_create_worker); | |
886 | ||
887 | /** | |
888 | * kthread_create_worker_on_cpu - create a kthread worker and bind it | |
7b7b8a2c | 889 | * to a given CPU and the associated NUMA node. |
fbae2d44 | 890 | * @cpu: CPU number |
dbf52682 | 891 | * @flags: flags modifying the default behavior of the worker |
fbae2d44 PM |
892 | * @namefmt: printf-style name for the kthread worker (task). |
893 | * | |
894 | * Use a valid CPU number if you want to bind the kthread worker | |
895 | * to the given CPU and the associated NUMA node. | |
896 | * | |
897 | * A good practice is to add the cpu number also into the worker name. | |
898 | * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu). | |
899 | * | |
ebb2bdce PM |
900 | * CPU hotplug: |
901 | * The kthread worker API is simple and generic. It just provides a way | |
902 | * to create, use, and destroy workers. | |
903 | * | |
904 | * It is up to the API user how to handle CPU hotplug. They have to decide | |
905 | * how to handle pending work items, prevent queuing new ones, and | |
906 | * restore the functionality when the CPU goes off and on. There are a | |
907 | * few catches: | |
908 | * | |
909 | * - CPU affinity gets lost when it is scheduled on an offline CPU. | |
910 | * | |
911 | * - The worker might not exist when the CPU was off when the user | |
912 | * created the workers. | |
913 | * | |
914 | * Good practice is to implement two CPU hotplug callbacks and to | |
915 | * destroy/create the worker when the CPU goes down/up. | |
916 | * | |
917 | * Return: | |
918 | * The pointer to the allocated worker on success, ERR_PTR(-ENOMEM) | |
fbae2d44 | 919 | * when the needed structures could not get allocated, and ERR_PTR(-EINTR) |
d25c83c6 | 920 | * when the caller was killed by a fatal signal. |
fbae2d44 PM |
921 | */ |
922 | struct kthread_worker * | |
dbf52682 PM |
923 | kthread_create_worker_on_cpu(int cpu, unsigned int flags, |
924 | const char namefmt[], ...) | |
fbae2d44 PM |
925 | { |
926 | struct kthread_worker *worker; | |
927 | va_list args; | |
928 | ||
929 | va_start(args, namefmt); | |
dbf52682 | 930 | worker = __kthread_create_worker(cpu, flags, namefmt, args); |
fbae2d44 PM |
931 | va_end(args); |
932 | ||
933 | return worker; | |
934 | } | |
935 | EXPORT_SYMBOL(kthread_create_worker_on_cpu); | |
936 | ||
37be45d4 PM |
937 | /* |
938 | * Returns true when the work could not be queued at the moment. | |
939 | * It happens when it is already pending in a worker list | |
940 | * or when it is being cancelled. | |
941 | */ | |
942 | static inline bool queuing_blocked(struct kthread_worker *worker, | |
943 | struct kthread_work *work) | |
944 | { | |
945 | lockdep_assert_held(&worker->lock); | |
946 | ||
947 | return !list_empty(&work->node) || work->canceling; | |
948 | } | |
949 | ||
8197b3d4 PM |
950 | static void kthread_insert_work_sanity_check(struct kthread_worker *worker, |
951 | struct kthread_work *work) | |
952 | { | |
953 | lockdep_assert_held(&worker->lock); | |
954 | WARN_ON_ONCE(!list_empty(&work->node)); | |
955 | /* Do not use a work with >1 worker, see kthread_queue_work() */ | |
956 | WARN_ON_ONCE(work->worker && work->worker != worker); | |
957 | } | |
958 | ||
9a2e03d8 | 959 | /* insert @work before @pos in @worker */ |
3989144f | 960 | static void kthread_insert_work(struct kthread_worker *worker, |
8197b3d4 PM |
961 | struct kthread_work *work, |
962 | struct list_head *pos) | |
9a2e03d8 | 963 | { |
8197b3d4 | 964 | kthread_insert_work_sanity_check(worker, work); |
9a2e03d8 | 965 | |
f630c7c6 RC |
966 | trace_sched_kthread_work_queue_work(worker, work); |
967 | ||
9a2e03d8 | 968 | list_add_tail(&work->node, pos); |
46f3d976 | 969 | work->worker = worker; |
ed1403ec | 970 | if (!worker->current_work && likely(worker->task)) |
9a2e03d8 TH |
971 | wake_up_process(worker->task); |
972 | } | |
973 | ||
b56c0d89 | 974 | /** |
3989144f | 975 | * kthread_queue_work - queue a kthread_work |
b56c0d89 TH |
976 | * @worker: target kthread_worker |
977 | * @work: kthread_work to queue | |
978 | * | |
979 | * Queue @work to work processor @task for async execution. @task | |
980 | * must have been created with kthread_worker_create(). Returns %true | |
981 | * if @work was successfully queued, %false if it was already pending. | |
8197b3d4 PM |
982 | * |
983 | * Reinitialize the work if it needs to be used by another worker. | |
984 | * For example, when the worker was stopped and started again. | |
b56c0d89 | 985 | */ |
3989144f | 986 | bool kthread_queue_work(struct kthread_worker *worker, |
b56c0d89 TH |
987 | struct kthread_work *work) |
988 | { | |
989 | bool ret = false; | |
990 | unsigned long flags; | |
991 | ||
fe99a4f4 | 992 | raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d4 | 993 | if (!queuing_blocked(worker, work)) { |
3989144f | 994 | kthread_insert_work(worker, work, &worker->work_list); |
b56c0d89 TH |
995 | ret = true; |
996 | } | |
fe99a4f4 | 997 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
b56c0d89 TH |
998 | return ret; |
999 | } | |
3989144f | 1000 | EXPORT_SYMBOL_GPL(kthread_queue_work); |
b56c0d89 | 1001 | |
22597dc3 PM |
1002 | /** |
1003 | * kthread_delayed_work_timer_fn - callback that queues the associated kthread | |
1004 | * delayed work when the timer expires. | |
fe5c3b69 | 1005 | * @t: pointer to the expired timer |
22597dc3 PM |
1006 | * |
1007 | * The format of the function is defined by struct timer_list. | |
1008 | * It should have been called from irqsafe timer with irq already off. | |
1009 | */ | |
fe5c3b69 | 1010 | void kthread_delayed_work_timer_fn(struct timer_list *t) |
22597dc3 | 1011 | { |
fe5c3b69 | 1012 | struct kthread_delayed_work *dwork = from_timer(dwork, t, timer); |
22597dc3 PM |
1013 | struct kthread_work *work = &dwork->work; |
1014 | struct kthread_worker *worker = work->worker; | |
ad01423a | 1015 | unsigned long flags; |
22597dc3 PM |
1016 | |
1017 | /* | |
1018 | * This might happen when a pending work is reinitialized. | |
1019 | * It means that it is used a wrong way. | |
1020 | */ | |
1021 | if (WARN_ON_ONCE(!worker)) | |
1022 | return; | |
1023 | ||
ad01423a | 1024 | raw_spin_lock_irqsave(&worker->lock, flags); |
22597dc3 PM |
1025 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
1026 | WARN_ON_ONCE(work->worker != worker); | |
1027 | ||
1028 | /* Move the work from worker->delayed_work_list. */ | |
1029 | WARN_ON_ONCE(list_empty(&work->node)); | |
1030 | list_del_init(&work->node); | |
6993d0fd Z |
1031 | if (!work->canceling) |
1032 | kthread_insert_work(worker, work, &worker->work_list); | |
22597dc3 | 1033 | |
ad01423a | 1034 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
22597dc3 PM |
1035 | } |
1036 | EXPORT_SYMBOL(kthread_delayed_work_timer_fn); | |
1037 | ||
bc88f85c BD |
1038 | static void __kthread_queue_delayed_work(struct kthread_worker *worker, |
1039 | struct kthread_delayed_work *dwork, | |
1040 | unsigned long delay) | |
22597dc3 PM |
1041 | { |
1042 | struct timer_list *timer = &dwork->timer; | |
1043 | struct kthread_work *work = &dwork->work; | |
1044 | ||
4b243563 | 1045 | WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn); |
22597dc3 PM |
1046 | |
1047 | /* | |
1048 | * If @delay is 0, queue @dwork->work immediately. This is for | |
1049 | * both optimization and correctness. The earliest @timer can | |
1050 | * expire is on the closest next tick and delayed_work users depend | |
1051 | * on that there's no such delay when @delay is 0. | |
1052 | */ | |
1053 | if (!delay) { | |
1054 | kthread_insert_work(worker, work, &worker->work_list); | |
1055 | return; | |
1056 | } | |
1057 | ||
1058 | /* Be paranoid and try to detect possible races already now. */ | |
1059 | kthread_insert_work_sanity_check(worker, work); | |
1060 | ||
1061 | list_add(&work->node, &worker->delayed_work_list); | |
1062 | work->worker = worker; | |
22597dc3 PM |
1063 | timer->expires = jiffies + delay; |
1064 | add_timer(timer); | |
1065 | } | |
1066 | ||
1067 | /** | |
1068 | * kthread_queue_delayed_work - queue the associated kthread work | |
1069 | * after a delay. | |
1070 | * @worker: target kthread_worker | |
1071 | * @dwork: kthread_delayed_work to queue | |
1072 | * @delay: number of jiffies to wait before queuing | |
1073 | * | |
1074 | * If the work has not been pending it starts a timer that will queue | |
1075 | * the work after the given @delay. If @delay is zero, it queues the | |
1076 | * work immediately. | |
1077 | * | |
1078 | * Return: %false if the @work has already been pending. It means that | |
1079 | * either the timer was running or the work was queued. It returns %true | |
1080 | * otherwise. | |
1081 | */ | |
1082 | bool kthread_queue_delayed_work(struct kthread_worker *worker, | |
1083 | struct kthread_delayed_work *dwork, | |
1084 | unsigned long delay) | |
1085 | { | |
1086 | struct kthread_work *work = &dwork->work; | |
1087 | unsigned long flags; | |
1088 | bool ret = false; | |
1089 | ||
fe99a4f4 | 1090 | raw_spin_lock_irqsave(&worker->lock, flags); |
22597dc3 | 1091 | |
37be45d4 | 1092 | if (!queuing_blocked(worker, work)) { |
22597dc3 PM |
1093 | __kthread_queue_delayed_work(worker, dwork, delay); |
1094 | ret = true; | |
1095 | } | |
1096 | ||
fe99a4f4 | 1097 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
22597dc3 PM |
1098 | return ret; |
1099 | } | |
1100 | EXPORT_SYMBOL_GPL(kthread_queue_delayed_work); | |
1101 | ||
9a2e03d8 TH |
1102 | struct kthread_flush_work { |
1103 | struct kthread_work work; | |
1104 | struct completion done; | |
1105 | }; | |
1106 | ||
1107 | static void kthread_flush_work_fn(struct kthread_work *work) | |
1108 | { | |
1109 | struct kthread_flush_work *fwork = | |
1110 | container_of(work, struct kthread_flush_work, work); | |
1111 | complete(&fwork->done); | |
1112 | } | |
1113 | ||
b56c0d89 | 1114 | /** |
3989144f | 1115 | * kthread_flush_work - flush a kthread_work |
b56c0d89 TH |
1116 | * @work: work to flush |
1117 | * | |
1118 | * If @work is queued or executing, wait for it to finish execution. | |
1119 | */ | |
3989144f | 1120 | void kthread_flush_work(struct kthread_work *work) |
b56c0d89 | 1121 | { |
46f3d976 TH |
1122 | struct kthread_flush_work fwork = { |
1123 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
1124 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
1125 | }; | |
1126 | struct kthread_worker *worker; | |
1127 | bool noop = false; | |
1128 | ||
46f3d976 TH |
1129 | worker = work->worker; |
1130 | if (!worker) | |
1131 | return; | |
b56c0d89 | 1132 | |
fe99a4f4 | 1133 | raw_spin_lock_irq(&worker->lock); |
8197b3d4 PM |
1134 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
1135 | WARN_ON_ONCE(work->worker != worker); | |
b56c0d89 | 1136 | |
46f3d976 | 1137 | if (!list_empty(&work->node)) |
3989144f | 1138 | kthread_insert_work(worker, &fwork.work, work->node.next); |
46f3d976 | 1139 | else if (worker->current_work == work) |
3989144f PM |
1140 | kthread_insert_work(worker, &fwork.work, |
1141 | worker->work_list.next); | |
46f3d976 TH |
1142 | else |
1143 | noop = true; | |
b56c0d89 | 1144 | |
fe99a4f4 | 1145 | raw_spin_unlock_irq(&worker->lock); |
b56c0d89 | 1146 | |
46f3d976 TH |
1147 | if (!noop) |
1148 | wait_for_completion(&fwork.done); | |
b56c0d89 | 1149 | } |
3989144f | 1150 | EXPORT_SYMBOL_GPL(kthread_flush_work); |
b56c0d89 | 1151 | |
34b3d534 PM |
1152 | /* |
1153 | * Make sure that the timer is neither set nor running and could | |
1154 | * not manipulate the work list_head any longer. | |
1155 | * | |
1156 | * The function is called under worker->lock. The lock is temporary | |
1157 | * released but the timer can't be set again in the meantime. | |
1158 | */ | |
1159 | static void kthread_cancel_delayed_work_timer(struct kthread_work *work, | |
1160 | unsigned long *flags) | |
1161 | { | |
1162 | struct kthread_delayed_work *dwork = | |
1163 | container_of(work, struct kthread_delayed_work, work); | |
1164 | struct kthread_worker *worker = work->worker; | |
1165 | ||
1166 | /* | |
1167 | * del_timer_sync() must be called to make sure that the timer | |
1168 | * callback is not running. The lock must be temporary released | |
1169 | * to avoid a deadlock with the callback. In the meantime, | |
1170 | * any queuing is blocked by setting the canceling counter. | |
1171 | */ | |
1172 | work->canceling++; | |
1173 | raw_spin_unlock_irqrestore(&worker->lock, *flags); | |
1174 | del_timer_sync(&dwork->timer); | |
1175 | raw_spin_lock_irqsave(&worker->lock, *flags); | |
1176 | work->canceling--; | |
1177 | } | |
1178 | ||
37be45d4 | 1179 | /* |
5fa54346 PM |
1180 | * This function removes the work from the worker queue. |
1181 | * | |
1182 | * It is called under worker->lock. The caller must make sure that | |
1183 | * the timer used by delayed work is not running, e.g. by calling | |
1184 | * kthread_cancel_delayed_work_timer(). | |
37be45d4 PM |
1185 | * |
1186 | * The work might still be in use when this function finishes. See the | |
1187 | * current_work proceed by the worker. | |
1188 | * | |
1189 | * Return: %true if @work was pending and successfully canceled, | |
1190 | * %false if @work was not pending | |
1191 | */ | |
5fa54346 | 1192 | static bool __kthread_cancel_work(struct kthread_work *work) |
37be45d4 | 1193 | { |
37be45d4 PM |
1194 | /* |
1195 | * Try to remove the work from a worker list. It might either | |
1196 | * be from worker->work_list or from worker->delayed_work_list. | |
1197 | */ | |
1198 | if (!list_empty(&work->node)) { | |
1199 | list_del_init(&work->node); | |
1200 | return true; | |
1201 | } | |
1202 | ||
1203 | return false; | |
1204 | } | |
1205 | ||
9a6b06c8 PM |
1206 | /** |
1207 | * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work | |
1208 | * @worker: kthread worker to use | |
1209 | * @dwork: kthread delayed work to queue | |
1210 | * @delay: number of jiffies to wait before queuing | |
1211 | * | |
1212 | * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise, | |
1213 | * modify @dwork's timer so that it expires after @delay. If @delay is zero, | |
1214 | * @work is guaranteed to be queued immediately. | |
1215 | * | |
d71ba164 | 1216 | * Return: %false if @dwork was idle and queued, %true otherwise. |
9a6b06c8 PM |
1217 | * |
1218 | * A special case is when the work is being canceled in parallel. | |
1219 | * It might be caused either by the real kthread_cancel_delayed_work_sync() | |
1220 | * or yet another kthread_mod_delayed_work() call. We let the other command | |
d71ba164 PM |
1221 | * win and return %true here. The return value can be used for reference |
1222 | * counting and the number of queued works stays the same. Anyway, the caller | |
1223 | * is supposed to synchronize these operations a reasonable way. | |
9a6b06c8 PM |
1224 | * |
1225 | * This function is safe to call from any context including IRQ handler. | |
1226 | * See __kthread_cancel_work() and kthread_delayed_work_timer_fn() | |
1227 | * for details. | |
1228 | */ | |
1229 | bool kthread_mod_delayed_work(struct kthread_worker *worker, | |
1230 | struct kthread_delayed_work *dwork, | |
1231 | unsigned long delay) | |
1232 | { | |
1233 | struct kthread_work *work = &dwork->work; | |
1234 | unsigned long flags; | |
d71ba164 | 1235 | int ret; |
9a6b06c8 | 1236 | |
fe99a4f4 | 1237 | raw_spin_lock_irqsave(&worker->lock, flags); |
9a6b06c8 PM |
1238 | |
1239 | /* Do not bother with canceling when never queued. */ | |
d71ba164 PM |
1240 | if (!work->worker) { |
1241 | ret = false; | |
9a6b06c8 | 1242 | goto fast_queue; |
d71ba164 | 1243 | } |
9a6b06c8 PM |
1244 | |
1245 | /* Work must not be used with >1 worker, see kthread_queue_work() */ | |
1246 | WARN_ON_ONCE(work->worker != worker); | |
1247 | ||
5fa54346 PM |
1248 | /* |
1249 | * Temporary cancel the work but do not fight with another command | |
1250 | * that is canceling the work as well. | |
1251 | * | |
1252 | * It is a bit tricky because of possible races with another | |
1253 | * mod_delayed_work() and cancel_delayed_work() callers. | |
1254 | * | |
1255 | * The timer must be canceled first because worker->lock is released | |
1256 | * when doing so. But the work can be removed from the queue (list) | |
1257 | * only when it can be queued again so that the return value can | |
1258 | * be used for reference counting. | |
1259 | */ | |
1260 | kthread_cancel_delayed_work_timer(work, &flags); | |
d71ba164 PM |
1261 | if (work->canceling) { |
1262 | /* The number of works in the queue does not change. */ | |
1263 | ret = true; | |
9a6b06c8 | 1264 | goto out; |
d71ba164 | 1265 | } |
5fa54346 | 1266 | ret = __kthread_cancel_work(work); |
9a6b06c8 | 1267 | |
9a6b06c8 PM |
1268 | fast_queue: |
1269 | __kthread_queue_delayed_work(worker, dwork, delay); | |
1270 | out: | |
fe99a4f4 | 1271 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
9a6b06c8 PM |
1272 | return ret; |
1273 | } | |
1274 | EXPORT_SYMBOL_GPL(kthread_mod_delayed_work); | |
1275 | ||
37be45d4 PM |
1276 | static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork) |
1277 | { | |
1278 | struct kthread_worker *worker = work->worker; | |
1279 | unsigned long flags; | |
1280 | int ret = false; | |
1281 | ||
1282 | if (!worker) | |
1283 | goto out; | |
1284 | ||
fe99a4f4 | 1285 | raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d4 PM |
1286 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
1287 | WARN_ON_ONCE(work->worker != worker); | |
1288 | ||
5fa54346 PM |
1289 | if (is_dwork) |
1290 | kthread_cancel_delayed_work_timer(work, &flags); | |
1291 | ||
1292 | ret = __kthread_cancel_work(work); | |
37be45d4 PM |
1293 | |
1294 | if (worker->current_work != work) | |
1295 | goto out_fast; | |
1296 | ||
1297 | /* | |
1298 | * The work is in progress and we need to wait with the lock released. | |
1299 | * In the meantime, block any queuing by setting the canceling counter. | |
1300 | */ | |
1301 | work->canceling++; | |
fe99a4f4 | 1302 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
37be45d4 | 1303 | kthread_flush_work(work); |
fe99a4f4 | 1304 | raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d4 PM |
1305 | work->canceling--; |
1306 | ||
1307 | out_fast: | |
fe99a4f4 | 1308 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
37be45d4 PM |
1309 | out: |
1310 | return ret; | |
1311 | } | |
1312 | ||
1313 | /** | |
1314 | * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish | |
1315 | * @work: the kthread work to cancel | |
1316 | * | |
1317 | * Cancel @work and wait for its execution to finish. This function | |
1318 | * can be used even if the work re-queues itself. On return from this | |
1319 | * function, @work is guaranteed to be not pending or executing on any CPU. | |
1320 | * | |
1321 | * kthread_cancel_work_sync(&delayed_work->work) must not be used for | |
1322 | * delayed_work's. Use kthread_cancel_delayed_work_sync() instead. | |
1323 | * | |
1324 | * The caller must ensure that the worker on which @work was last | |
1325 | * queued can't be destroyed before this function returns. | |
1326 | * | |
1327 | * Return: %true if @work was pending, %false otherwise. | |
1328 | */ | |
1329 | bool kthread_cancel_work_sync(struct kthread_work *work) | |
1330 | { | |
1331 | return __kthread_cancel_work_sync(work, false); | |
1332 | } | |
1333 | EXPORT_SYMBOL_GPL(kthread_cancel_work_sync); | |
1334 | ||
1335 | /** | |
1336 | * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and | |
1337 | * wait for it to finish. | |
1338 | * @dwork: the kthread delayed work to cancel | |
1339 | * | |
1340 | * This is kthread_cancel_work_sync() for delayed works. | |
1341 | * | |
1342 | * Return: %true if @dwork was pending, %false otherwise. | |
1343 | */ | |
1344 | bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *dwork) | |
1345 | { | |
1346 | return __kthread_cancel_work_sync(&dwork->work, true); | |
1347 | } | |
1348 | EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync); | |
1349 | ||
b56c0d89 | 1350 | /** |
3989144f | 1351 | * kthread_flush_worker - flush all current works on a kthread_worker |
b56c0d89 TH |
1352 | * @worker: worker to flush |
1353 | * | |
1354 | * Wait until all currently executing or pending works on @worker are | |
1355 | * finished. | |
1356 | */ | |
3989144f | 1357 | void kthread_flush_worker(struct kthread_worker *worker) |
b56c0d89 TH |
1358 | { |
1359 | struct kthread_flush_work fwork = { | |
1360 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
1361 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
1362 | }; | |
1363 | ||
3989144f | 1364 | kthread_queue_work(worker, &fwork.work); |
b56c0d89 TH |
1365 | wait_for_completion(&fwork.done); |
1366 | } | |
3989144f | 1367 | EXPORT_SYMBOL_GPL(kthread_flush_worker); |
35033fe9 PM |
1368 | |
1369 | /** | |
1370 | * kthread_destroy_worker - destroy a kthread worker | |
1371 | * @worker: worker to be destroyed | |
1372 | * | |
1373 | * Flush and destroy @worker. The simple flush is enough because the kthread | |
1374 | * worker API is used only in trivial scenarios. There are no multi-step state | |
1375 | * machines needed. | |
eb79fa7e Z |
1376 | * |
1377 | * Note that this function is not responsible for handling delayed work, so | |
1378 | * caller should be responsible for queuing or canceling all delayed work items | |
1379 | * before invoke this function. | |
35033fe9 PM |
1380 | */ |
1381 | void kthread_destroy_worker(struct kthread_worker *worker) | |
1382 | { | |
1383 | struct task_struct *task; | |
1384 | ||
1385 | task = worker->task; | |
1386 | if (WARN_ON(!task)) | |
1387 | return; | |
1388 | ||
1389 | kthread_flush_worker(worker); | |
1390 | kthread_stop(task); | |
eb79fa7e | 1391 | WARN_ON(!list_empty(&worker->delayed_work_list)); |
35033fe9 PM |
1392 | WARN_ON(!list_empty(&worker->work_list)); |
1393 | kfree(worker); | |
1394 | } | |
1395 | EXPORT_SYMBOL(kthread_destroy_worker); | |
05e3db95 | 1396 | |
f5678e7f CH |
1397 | /** |
1398 | * kthread_use_mm - make the calling kthread operate on an address space | |
1399 | * @mm: address space to operate on | |
9bf5b9eb | 1400 | */ |
f5678e7f | 1401 | void kthread_use_mm(struct mm_struct *mm) |
9bf5b9eb CH |
1402 | { |
1403 | struct mm_struct *active_mm; | |
1404 | struct task_struct *tsk = current; | |
1405 | ||
f5678e7f CH |
1406 | WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); |
1407 | WARN_ON_ONCE(tsk->mm); | |
1408 | ||
9bf5b9eb | 1409 | task_lock(tsk); |
38cf307c PZ |
1410 | /* Hold off tlb flush IPIs while switching mm's */ |
1411 | local_irq_disable(); | |
9bf5b9eb CH |
1412 | active_mm = tsk->active_mm; |
1413 | if (active_mm != mm) { | |
1414 | mmgrab(mm); | |
1415 | tsk->active_mm = mm; | |
1416 | } | |
1417 | tsk->mm = mm; | |
618758ed | 1418 | membarrier_update_current_mm(mm); |
38cf307c PZ |
1419 | switch_mm_irqs_off(active_mm, mm, tsk); |
1420 | local_irq_enable(); | |
9bf5b9eb CH |
1421 | task_unlock(tsk); |
1422 | #ifdef finish_arch_post_lock_switch | |
1423 | finish_arch_post_lock_switch(); | |
1424 | #endif | |
1425 | ||
618758ed MD |
1426 | /* |
1427 | * When a kthread starts operating on an address space, the loop | |
1428 | * in membarrier_{private,global}_expedited() may not observe | |
1429 | * that tsk->mm, and not issue an IPI. Membarrier requires a | |
1430 | * memory barrier after storing to tsk->mm, before accessing | |
1431 | * user-space memory. A full memory barrier for membarrier | |
1432 | * {PRIVATE,GLOBAL}_EXPEDITED is implicitly provided by | |
1433 | * mmdrop(), or explicitly with smp_mb(). | |
1434 | */ | |
9bf5b9eb CH |
1435 | if (active_mm != mm) |
1436 | mmdrop(active_mm); | |
618758ed MD |
1437 | else |
1438 | smp_mb(); | |
9bf5b9eb | 1439 | } |
f5678e7f | 1440 | EXPORT_SYMBOL_GPL(kthread_use_mm); |
9bf5b9eb | 1441 | |
f5678e7f CH |
1442 | /** |
1443 | * kthread_unuse_mm - reverse the effect of kthread_use_mm() | |
1444 | * @mm: address space to operate on | |
9bf5b9eb | 1445 | */ |
f5678e7f | 1446 | void kthread_unuse_mm(struct mm_struct *mm) |
9bf5b9eb CH |
1447 | { |
1448 | struct task_struct *tsk = current; | |
1449 | ||
f5678e7f CH |
1450 | WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); |
1451 | WARN_ON_ONCE(!tsk->mm); | |
1452 | ||
9bf5b9eb | 1453 | task_lock(tsk); |
618758ed MD |
1454 | /* |
1455 | * When a kthread stops operating on an address space, the loop | |
1456 | * in membarrier_{private,global}_expedited() may not observe | |
1457 | * that tsk->mm, and not issue an IPI. Membarrier requires a | |
1458 | * memory barrier after accessing user-space memory, before | |
1459 | * clearing tsk->mm. | |
1460 | */ | |
1461 | smp_mb__after_spinlock(); | |
9bf5b9eb | 1462 | sync_mm_rss(mm); |
38cf307c | 1463 | local_irq_disable(); |
9bf5b9eb | 1464 | tsk->mm = NULL; |
618758ed | 1465 | membarrier_update_current_mm(NULL); |
9bf5b9eb CH |
1466 | /* active_mm is still 'mm' */ |
1467 | enter_lazy_tlb(mm, tsk); | |
38cf307c | 1468 | local_irq_enable(); |
9bf5b9eb CH |
1469 | task_unlock(tsk); |
1470 | } | |
f5678e7f | 1471 | EXPORT_SYMBOL_GPL(kthread_unuse_mm); |
9bf5b9eb | 1472 | |
0b508bc9 | 1473 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
1474 | /** |
1475 | * kthread_associate_blkcg - associate blkcg to current kthread | |
1476 | * @css: the cgroup info | |
1477 | * | |
1478 | * Current thread must be a kthread. The thread is running jobs on behalf of | |
1479 | * other threads. In some cases, we expect the jobs attach cgroup info of | |
1480 | * original threads instead of that of current thread. This function stores | |
1481 | * original thread's cgroup info in current kthread context for later | |
1482 | * retrieval. | |
1483 | */ | |
1484 | void kthread_associate_blkcg(struct cgroup_subsys_state *css) | |
1485 | { | |
1486 | struct kthread *kthread; | |
1487 | ||
1488 | if (!(current->flags & PF_KTHREAD)) | |
1489 | return; | |
1490 | kthread = to_kthread(current); | |
1491 | if (!kthread) | |
1492 | return; | |
1493 | ||
1494 | if (kthread->blkcg_css) { | |
1495 | css_put(kthread->blkcg_css); | |
1496 | kthread->blkcg_css = NULL; | |
1497 | } | |
1498 | if (css) { | |
1499 | css_get(css); | |
1500 | kthread->blkcg_css = css; | |
1501 | } | |
1502 | } | |
1503 | EXPORT_SYMBOL(kthread_associate_blkcg); | |
1504 | ||
1505 | /** | |
1506 | * kthread_blkcg - get associated blkcg css of current kthread | |
1507 | * | |
1508 | * Current thread must be a kthread. | |
1509 | */ | |
1510 | struct cgroup_subsys_state *kthread_blkcg(void) | |
1511 | { | |
1512 | struct kthread *kthread; | |
1513 | ||
1514 | if (current->flags & PF_KTHREAD) { | |
1515 | kthread = to_kthread(current); | |
1516 | if (kthread) | |
1517 | return kthread->blkcg_css; | |
1518 | } | |
1519 | return NULL; | |
1520 | } | |
05e3db95 | 1521 | #endif |